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The autumn of 2017, OpenVPN Technologies, Inc changed name to just OpenVPN Inc. Otherwise, extend the copyright to cover 2018 as well. With the exception of the company name change, all changes have been performed by the dev-tools/update-copyright.sh script. Signed-off-by: David Sommerseth <davids@openvpn.net> Acked-by: Gert Doering <gert@greenie.muc.de> Message-Id: <20180131140314.11103-1-davids@openvpn.net> URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg16418.html Signed-off-by: Gert Doering <gert@greenie.muc.de>
103 lines
4.4 KiB
C
103 lines
4.4 KiB
C
/*
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* OpenVPN -- An application to securely tunnel IP networks
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* over a single TCP/UDP port, with support for SSL/TLS-based
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* session authentication and key exchange,
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* packet encryption, packet authentication, and
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* packet compression.
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*
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* Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
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*
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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/**
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* @file
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* Data Channel Control module documentation file.
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*/
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/**
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* @defgroup data_control Data Channel Control module
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*
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* This module controls the processing of packets as they pass through the
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* data channel.
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*
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* The Data Channel Control module controls the processing of packets as
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* they pass through the data channel. The processing includes packet
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* compression, fragmentation, and the performing of security operations
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* on the packets. This module does not do the processing itself, but
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* passes the packet to other data channel modules to perform the
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* appropriate actions.
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*
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* Packets can travel in two directions through the data channel. They
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* can be going to a remote destination which is reachable through a VPN
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* tunnel, in which case this module prepares them to be sent out through
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* a VPN tunnel. On the other hand, they can have been received through a
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* VPN tunnel from a remote OpenVPN peer, in which case this module
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* retrieves the packet in its original form as it was before entering the
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* VPN tunnel on the remote OpenVPN peer. How this module processes
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* packets traveling in the two directions is discussed in more detail
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* below.
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*
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* @par Packets to be sent to a remote OpenVPN peer
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* This module's main function for processing packets traveling in this
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* direction is \c encrypt_sign(), which performs the following processing
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* steps:
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* - Call the \link compression Data Channel Compression module\endlink to
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* perform packet compression if necessary.
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* - Call the \link fragmentation Data Channel Fragmentation
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* module\endlink to perform packet fragmentation if necessary.
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* - Call the \link data_crypto Data Channel Crypto module\endlink to
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* perform the required security operations.
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*
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* @par
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* See the \c encrypt_sign() documentation for details of these
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* interactions.
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*
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* @par
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* After the above processing is complete, the packet is ready to be sent
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* to a remote OpenVPN peer as a VPN tunnel packet. The actual sending of
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* the packet is handled by the \link external_multiplexer External
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* Multiplexer\endlink.
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*
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* @par Packets received from a remote OpenVPN peer
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* The function that controls how packets traveling in this direction are
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* processed is \c process_incoming_link(). That function, however, also
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* performs some of the tasks required for the \link external_multiplexer
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* External Multiplexer\endlink and is therefore listed as part of that
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* module, instead of here.
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*
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* @par
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* After the \c process_incoming_link() function has determined that a
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* received packet is a data channel packet, it performs the following
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* processing steps:
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* - Call the \link data_crypto Data Channel Crypto module\endlink to
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* perform the required security operations.
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* - Call the \link fragmentation Data Channel Fragmentation
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* module\endlink to perform packet reassembly if necessary.
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* - Call the \link compression Data Channel Compression module\endlink to
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* perform packet decompression if necessary.
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*
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* @par
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* See the \c process_incoming_link() documentation for details of these
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* interactions.
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*
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* @par
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* After the above processing is complete, the packet is in its original
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* form again as it was received by the remote OpenVPN peer. It can now
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* be routed further to its final destination. If that destination is a
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* locally reachable host, then the \link internal_multiplexer Internal
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* Multiplexer\endlink will send it there.
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*/
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